The present invention generally relates to semiconductor manufacturing processes, and more specifically relates to a method and apparatus for making a semiconductor wherein a low k film is laminated on a wafer.
A current problem in the semiconductor manufacturing industry is the inability to successfully integrate new low K materials (K<2.7) into sub 0.13 micron process nodes. The problem exists because materials which are currently being used cannot structurally handle repeated CMP processing. Specifically, the porosity of the materials delaminate or collapse.
Currently, this field is an area of large amounts of research and development. There are constantly new materials and process techniques being developed in an attempt to solve this problem. The documentation that is currently available questions the industry's ability to achieve the necessary process requirements to keep pace with the advancing technologies (i.e., 0.13, 0.09, 0.065 micron process nodes). One solution to this problem that has been attempted, and has been widely published, is the development of a replacement process for CMP, often referred to as “stress free polishing.” This technique utilizes reverse electro plating technology, a technology which has existed (in other areas) for many years. By using reverse electro plating technology, a lower K material can be used, and the copper can be polished by this process as opposed to the more stressful and damaging CMP methods that cause damage to the low K films. Currently, this process is still in its development stages, and has yet been proven to be a viable and reliable process replacement for CMP.
A disadvantage of the new materials that have been developed recently is that they do not have the structural integrity and reliability to withstand repeated CMP polishes and maintain their topography. More porosity is needed to achieve the lower K value. Air has a K value of 1.0; therefore, to lower the K value of a film, air spaces need to be added. These spaces can become sources for residual contamination or collapse that can harm subsequent deposited film layers. They can also trap residuals from a liquid source deposition that can explode upon expansion during the heat treating of a film.